The identification of synthetic organic pigments in modern paints and modern paintings using pyrolysis-gas chromatography–mass spectrometry

A collection of more than 70 synthetic organic pigments were analysed using pyrolysis-gas chromatography–mass spectrometry (Py-GC–MS). We report on the analysis of diketo-pyrrolo-pyrrole, isoindolinone and perylene pigments which are classes not previously reported as being analysed by this technique. We also report on a number of azo pigments (2-naphthol, naphthol AS, arylide, diarylide, benzimidazolone and disazo condensation pigments) and phthalocyanine pigments, the Py-GC–MS analysis of which has not been previously reported. The members of each class were found to fragment in a consistent way and the pyrolysis products are reported. The technique was successfully applied to the analysis of paints used by the artist Francis Bacon (1909–1992), to simultaneously identify synthetic organic pigments and synthetic binding media in two samples of paint taken from Bacon’s studio and micro-samples taken from three of his paintings and one painting attributed to him. Figure Dulux orange paint in the studio of Francis Bacon, now located at Dublin City Gallery, The Hugh Lane